No. 7. DEPARTMENT OF AGRICULTURE. 195 



its adaptability or quality for making lime-sulfur wasli. These 

 lime investigations are not yet completed, but one of the important 

 points determined beyond question is that the color of the lime- 

 sulfur wash is not due to the kind of lime that is used, in regard to 

 contents of magnesia or calcium, as has been supposed and pub- 

 lished, but that it is due to the presence or absence of iron or 

 manganese. Where either of these materials be present, even in 

 slight quantity, the color of the boiled lime-sulfur wash becomes 

 dark, muddy olive green, while Avhen no iron or manganese is con- 

 tained in the lime, the color remains about the same as cooked 

 tomatoes. 



Another important result of our practical studies in the orchard 

 and laboratory from numerous samples, is the determination of the 

 fact that the carbonic acid gas when used as a power for spraying, 

 as in the gas sprayers, disintegrates or breaks up the combination of 

 the calcium sulfide in the lime-sulfur wash and precipitates nearly 

 half the material in solution after a half hour's time. A remarkable 

 feature is, that about forty per cent, of it is precipitated during the 

 first five minutes. More is to be published on this subject in our 

 Monthly Bulletin soon. 



In our investigations with lime-sulfur wash we learned that there 

 is a great variation in the compositions of these materials. Some of 

 the manufacturers who have most loudly proclaimed the great super- 

 iority of their goods have placed on the market materials contain- 

 ing less of the lime-sulfur combinations than others, and there 

 seems to be as ret no standard composition for these materials. 

 This year has seen the development of a great number of companies 

 manufacturing the lime-sulfur wash. The product of some com- 

 panies has upon examination, in the laboratory been found to be 

 fully twice as strong as the product made by others. 



In field test and orchard observations we have found that it is 

 necessary to warn the public against too great dilution of commercial 

 insecticides, and especially of all materials recommended for San 

 Jop(^ Scalp. With the oils the difTicnlty is that if used strong enough 

 to kill the scale they are liable to injure the tree, and they often do 

 so. Tliis is not true of the lime-sulfur wash, either home made or 

 commercial. We should add that we did not find one sample of 

 the commercial lime-sulfur wash that was as strong chemically as 

 the home-boiled, when made in accordance with the now standard 

 formula of seventeen pounds of sulfur and twenty-two pounds of 

 Hime to fifty gallons of water, boiled one hour. We found that 

 manufacturers of the lime-sulfur wash make a mistake in recom- 

 mending dilution of their product to the extent of ten or eleven 

 times their bulk of water, and we can not, in general, recommend 

 the commercial lime-snlfur wash to be dilute at any time with more 

 than eight times its bulk of water if satisfactory results are to be 

 obtained. 



13. INSTRUCTION. 



The information which we liave obtained from investigations and 

 experiments have been given to the public extonsively through the 

 press, through our IMonthly Bulletins, Annual Reports and espec- 

 ially Addresses. This office has co-operated with the Division of 

 Farmers' Institutes, furnishing speakers whenever required. Also, 

 we have held many orchard meetings, and have even tried success- 



